1. Field of the Invention
The present invention relates to a liquid ejection head capable of ejecting a liquid through an ejection port, specifically relates to a structure of a liquid ejection head suitable for removing the liquid adhered to a face of the liquid ejection head, provided with the ejection port, (hereinafter referred to as the “ejection face”).
2. Description of the Related Art
An ink jet printing apparatus which forms an image on a printing medium using a liquid ejection head may generate fine ink droplets which do not land on the printing medium. These fine ink droplets become ink mist that floats between the liquid ejection head and the printing medium. Thus, there is a problem that the ink mist adheres, in some cases, particularly to an orifice plate which is a member forming the ejection face of the liquid ejection heads. FIG. 13 shows a schematic drawing illustrating the adhered state of ink onto the orifice plate. According to the orifice plate shown in FIG. 13, there are two parallel arrays of ejection ports, and ink adheres to the periphery of the ejection ports.
As illustrated in FIG. 13, the ink ejected from the liquid ejection head and adhering to the orifice plate is largely grouped into two kinds depending on the adhesion zone. That is, one is the mist in the adhesion zone in a lip shape adhering surrounding the ejection port array, (hereinafter referred to as the “lip mist”), and the other is the mist in the adhesion zone adhering between the two arrays of ejection ports, (hereinafter referred to as the “mist between ejection port arrays”).
For the ink adhering onto the orifice plate of the liquid ejection head as described above, a printing apparatus of serial scan type commonly removes the adhered ink by cleaning action that wipes the ejection face. The printing apparatus of serial scan type is a printing apparatus which forms an image by ejecting the liquid from the liquid ejection head while scanning the liquid ejection head in the direction perpendicular to the direction of conveying the printing medium. A cleaner removes the deposited ink by wiping the orifice plate on which the mist accumulates using a wiper blade member on a rubber plate. When cleaning of the liquid ejection head is performed, the printing action is temporarily stopped cleaning.
There are available ink jet printing apparatuses that improve printing speed by increasing the size of the liquid ejection head, or widening the range of arrangement of ejection port arrays, thus decreasing the scanning cycles of the liquid ejection head. Furthermore, as disclosed in Japanese Patent Laid-Open No. 6-008446 (1994), there is a full-line printing type which performs image-forming while the printing medium is conveyed against the fixed liquid ejection head on which the ejection ports are arranged over the range corresponding to the width of the printing medium.
Under the condition that the ejection port array is elongated as described above, the cleaning to remove the adhered mist accumulated during the printing action takes a longer time for a single cleaning cycle. This leads to the increase in the period of intermission of printing process, which is a problem on attaining high speed printing of the printing apparatus.
If the orifice plate is not cleaned in order to increase the speed of printing, the lip mist A and the mist between ejection port arrays B respectively accumulate, as illustrated in FIG. 13. When the respective depositions further increase, there is formed a puddle of ink as a result of connecting the lip mist A with the mist between ejection port arrays B overpassing the respective ejection port arrays. Covering the ejection port with the puddle of ink may prevent the ink from being ejected. Specifically, the mist between ejection port arrays B may affect the ink ejection performance even with a small amount of adhered mist, because generally the distance between the two ejection port arrays is small (normally 200 μm).